Means for defrosting cooling element of mechanical refrigerators



Jan. 9, 1934. 1,942,412

MEANS FOR DEFROSTING COOLING ELEMENT OF MECHANICAL REFRIGEHATORS J. AQDIENNER' ET AL Filed Aug. 22. 192'! Jo/z 12 E Garcia 67" A a: N o 'l-l'amzgys.

Patented Jan. 9, 1934 UNITED STATES PATENT OFFICE MEANS FOR DEFROSTING COOLING ELE- MENT OF MECHANICAL REFRIGERATORS John A. Dienner, Eganston, and John E. Gardner,

16 Claims.

Our invention relates in general to mechanical refrigerators and more particularly to means for defrosting the cooling element of such refrigerators. In mechanical refrigerators it has always been a great problem to prevent frosting as much as possible in order to maintain the operating efficiency of the device. When frost collects on the cooling element of a mechanical refrigerator, as it does very quickly from the moisture in the air, an insulating coating of ice is formed over the cooling element. This coating of insulation on the cooling element of the refrigerator means that mechanical equipment, whereby the refrigerating action is brought about, must necessarily operate a great deal oftener and longer in order to maintain the refrigerator at its desired temperature. In addition this insulating coating of ice increases day by day and finally renders it very difiicult to get at the cooling element at all in order to remove the ice drawers, that are usually provided within the cooling element. In order to "removethese drawers it is necessary to 1 take a sharp instrument and'chip away the ice, taking great care not to pierce the metal of the cooling element. When this condition prevails it is necessary that the operator or home owner having the refrigerator shut it down manually so that it willno longer respond to the thermostatic control device in the refrigerator. The low temperature of the refrigerator is then maintained by the melting of the frost or insulating ice coating. After this coating has melted entirely away it is again necessary to manually reconnect the 35 mechanical refrigerating apparatus. Under this procedure, there is great danger of the home owner forgetting to reconnect the refrigerator at the proper time, or being unable to do so. Under these conditions the refrigerating compartment 1, of the refrigerator, is not maintained at its proper temperature and the food that it is desired'to preserve within the device is very likely to be spoiled.

The principal object of our invention is to over come all the above difficulties by providing means for automatically bringing about this defrosting operation whichneeds no attention from the refrigerator operator or home owner whatsoever.

Another object of our invention is to provide means responsive to the formation of an insulating ice coating about the cooling element.

Another object is to provide'means controlled 1 by this device which is responsive to the frosting of the cooling element for disabling the refrigerating apparatus.

refrigerating cabinet proper.

' pressor 5 -In fact, all the apparatus RussuEo Another object is to provide means responsive to theremoval of the ice or insulating coating for automatically rendering the mechanical refrigerating mechanism again operable.

There are other objects of our invention, which go together with the foregoing, will be described in the detailed specification which is to follow taken in conjunction with the accompanying drawing.

In practicing our invention we provide a thermal element which is responsive directly to 35 the temperature of the refrigerating or cooling element and we also provide a. thermal element which is responsive to the temperature of the Means are provided for automatically opening the circuit of the motor controlling the electric compressor, where v such compressor is used to provide the refrigeration, when the temperature within the cooling device proper is below the temperature of the refrigerator. A thermally controlled switch is also employed for automatically operating the refrigerating mechanism under normal conditions, but its operation is without effect if an insulating frosting is present on the outside of the cooling element for the reasons above stated.

While in the drawing we have shown our invention applied to an electric type of refrigerator, it will be understood from the drawing and description how the same principle may be employed inany mechanical refrigerator to "per- 5 form the same functions.

It will be appreciated that while we have shown a more or less diagrammatic view of the various elements of an electric mechanical refrigerator that they may be of any well known or suitable type. I

In the drawing, we have shown a sectional viewof an electric mechanical refrigerator with certain of the elements in side elevation.

Referring to the drawing, the reference character 1 designates any usual type of refrigerator box provided with a refrigerating compartment 2 and a compartment 3 containing the mechanism. This mechanism may be of any suitable, or well known type and comprises essentially an electric motor 4 driving a compressor 5. The refrigerating fluid is transmitted from the comto the cooling or condensing coil 6 through the pipe 7 and the expansion'valve 8 through the cooling coils, (not shown) in the brine tank 9, and thence back to the compressor through the pipe 10. The condensing coil 6 may be cooled in any suitable or well known manner.

just described is of any suitable or well known type. The circuit of g for the same reasons.

the electric motor 4 is controlled by a fluid controlled thermostatic snap switch 11 of any usual or well known construction. The thermostat 11 is operated through the medium of a fluid in the pipe 12 which is provided with a thermoresponsive portion 13, which is suitably immersed in a small brine tank 14. The reason for this provision, whereby the thermoresponsive element 13 controlling the fluid which operates the thermostat 11 is immersed in a small brine tank, is to render its action somewhat sluggish so that momentary opening of the door leading to the refrigerating compartment 2 of the refrigerator 1 will not bring about intermittent operation of the electric motor 4 and the compressor unit 5.

The circuit of the electric motor is also controlled by a snap switch 15, which may be of any well known or suitable construction. This snap switch is controlled by two bellows 16 and 1'7. The bellows 16 is controlled through the medium of a fluid acting in the pipe 18 from the thermoresponsive element 19 emerged in the brine tank 9 adjacent to the regularcooling coils of the refrigerator. The bellows 16 controlling the action of the snap switch 15 is thus directly responsive to the temperature maintained by the cooling coils within the brine tank, which is unaffected by the coating of frost or insulating ice that forms about the outside of the brine tank under and around the drawers 20, 21 and 22, for example, associated with the brine tank under usual operating conditions.

The snap switch 15 is also controlled by a bellows 1'7 which is operated by a fluid acting in the pipe 23. This fluid is controlled by the thermal element 24 which is immersed in a small brine tank 25 in the same manner that the element 13 is immersed in a small brine tank 14 and Obviously these two brine tanks may be combined. The bellows 1'7 is thus controlled and is directly responsive to the temperature maintained in the refrigerating compartment 2 of the refrigerator. The snap switch 15 which is adapted to be operated by the conjoint action of the bellows 16 and 1'7 is adapted to open its contacts 26 when the temperature of the brine solution is a predetermined .amount below the temperature of the refrigerating com- I partment of the refrigerator. This is indicated diagrammatically in the drawing where a contraction of the fluid in the bellows 16 causes the movement of .theelement 2'7 about its pivot 28 in a downward direction, while a rise in temperature in the refrigerating compartment tends to expand the bellows 1'7, thereby bringing about the opening movement of the contact making -member.26.

So long as the temperatures at both points are maintained substantially alikejwithin predetermined limits the action of the bellows 16 and 1'7 counterbalance each other and the operation of the refrigerator is directly controlled by the thermostat switch 11 in any usual or well known manner. That is, so long as there is no appreciable coating of frost or ice on the outside of the brine tank, the action of the refrigerator proceeds in any usual or well known manner under the control of the thermostat switch 11, so that the proper temperature is maintained within the refrigerating compartment 2. However, as soon as there is a thick enough insulating coating of frost or ice on the outside of the brine tank, the ready transfer of heat from the refrigerating compartment to the cooling element in the brine tank 9 is retarded and inhibited.

,22 to become readily accessible. In addition, our

The mechanical refrigerating equipment comprising the motor 4 and the compressor 5 is thus maintained in operation to still further reduce the temperature of the brine tank in an attempt to reduce the temperature within the refrigerating compartment the requisite amount. This brings about a differential action between the bellows 16 and the bellows 17 controlling the thermostat switch 15. When a predetermined differential is reached the contact making member 26 of the thermostat switch 15 is moved away from its associated contact member and the circuit of the compressor and the motor is permanently opened irrespective of the position of the thermostatic switch 11, controlling the normal operation of the refrigerator. The temperature within the refrigerating compartment 2 of the refrigerator is then maintained by the melting of the coating of ice or frost on the brine tank, since the mechanical refrigerating equipment can no longer be operated. When the ice and frostis melted away the temperature of the brine tank rises and the bellows 16 expands. Under these conditions there is no longer a differential in temperature between the brine tank 9 and the refrigerating compartment 2 and there is no differential between the bellows 16 and the bellows 1'7, consequently the contact making member 26 is brought into engagement with its I associated contact member and the circuit of the thermostat switch 11 and the operation of the refrigerating system proceeds as before. The water formed by the melting of the ice and frost about the brine tank may be carried'away by a suitable pan or in any other approved or well known manner. The predetermined differential in temperature governing the operation of .the bellows 16 and 1'7 controlling the snap switch 15 may be brought about by the adjustment of the follow-through of the contact member associated with the contact making member 26.

The operation of the refrigerator now proceeds, asbefore, under the control of the thermostatic snap switch 11 until another insulating coating of frost or ice, sufficient to bring about the required temperature differential is formed, when the same operations are repeated.

From the foregoing, it will be seen that we have provided means for automatically bringing about the defrosting of the cooling element of a mechanical refrigerator. By our invention the frost or ice is caused to melt to remove the insulating coating and to permit the ice drawers 20, 21 and invention provides means for preventing the unnecessary movement of the mechanical refrigcrating equipment with its consequent wear and tear on the apparatus in addition to the usual use of power in a vain attempt to maintain the required temperature within the refrigerating compartment. Also, our invention provides means for automatically initiating the operation of the mechanical refrigerating equipment as soon as the frost or ice condition is removed so as to continuously maintain the temperature within the refrigerating compartment at the proper degree.

It will be understood that the differential control element 15 comprising the interacting bellows 16 and 17 may be also employed to control 145 a valve governing agas operated refrigerator or, in fact, any type of mechanical refrigerator in a manner that will be obvious from the foregoing description.

While we have shown and described one embodiment of our invention, we are aware that many changes, modifications and deviations may be made, as it will be understood that we desire to protect-by Letters Patent all such changes, modifications, deviations as come within the scope of the appended claims.

' We claim:

1. In a refrigerator, a refrigerating compartment and a cooling element associated with said compartment, mechanically operated means for lowering the temperature of said cooling element,

a thermal responsive device responsive to the temperature of said cooling element, and a thermal responsive device responsive to the temperature of said compartment, and means for controlling said mechanical means in accordance with the temperature differential between said thermal responsive devices.

2. A refrigerator comprising the combination of meansproviding a refrigerating compartment, means for driving a fluid therethrough, a cooling element within the compartment, and temperature responsive means operative whenever the difference between the temperature of the cooling element and the temperature in the refrigerating compartment reaches a predetermined value for stopping the fluid driving means.

3. A refrigerator comprising the combination of a refrigerating compartment, cooling means to cool said compartment, mechanical means to lower the temperature of 'said cooling means, and means to automatically control the mechanical means in accordance with the difference of temperature between the compartment and the cooling means.

4. A refrigerator comprising the combination of a refrigerating compartment, cooling means to cool said compartment, mechanical means to lower the temperature of said cooling means, means to automatically control the mechanical means in accordance with the difference of temperature between the compartment and the cooling means, and means acting serially with said automatic means to control the mechanical means in accordance with the temperature of said compartment.

5. In combination, a cooling chamber having a fluid expansion member for extracting heat from said chamber, a compressor for compressing fluid for said member, and thermally controlled means subject to the difference in temperature between the chamber and the member for preventing the operation of said compressor.

6. In combination, a cooling chamber having a fluid expansion cooled device for extracting heat from said chamber, means for compressing fluid for expansion to cool said device thermally controlled means subject to the difference in temperature between the chamber and the device for preventing the operation of said means, and thermally actuated means for controlling the temperature in said chamber. f

'7. In combination, a fluid containing chamber, a heat exchange device for absorbing heat from the fluid in the chamber, means for passing a cooling fluid through the heat exchange device to carry heat away from said device, a control device for said last named means and means responsive to a difference in temperature between the fluid in the chamber and the heat exchange device for actuating said control device.

8. In combination, arefrigerating chamber, a mechanical refrigerating system comprising a heat exchange device for cooling the chamber, an electric motor for operating the system, thermally controlled means for stopping and starting the motor in response to absolute temperature in the chamber, said last named means including a switch in the circuit of the motor, and thermally controlled means having a part in heat conduct-- ing relation to the heat exchange device and a part in heat'conducting relation to the air in the cooling chamber for interrupting the circuit of the motor, said last named meanscomprising a switch in series relation to the aforesaid switch.

9. In combination, a cooling chamber, a heat exchange device for extracting heat from said chamber, a motor for operating said device, a thermally actuated switch in said chamber for controlling said motor, and means disposed in said chamber away from said switch for retarding the actionofsaid switch.

[10. In combination, a cooling chamber, a heat exchange device for extracting heat from said chamber, a motor for controlling said device, thermally actuated means responsive to the temperature in said chamber for actuating said motor, secondary means responsive to the difference in temperature of said chamber'and said 11. Incombination, a cooling chamber, fluid heat exchange means for extracting heat from said chamber, means for controlling the flow of fluid through said heat exchange means, differential thermally actuated means responsive to the temperatures of said heat exchange means and of said chamber for rendering said fluid flow controlling means inoperative, and means in said chamber for retarding the action of said thermally actuated means.

12. In combination, a refrigerating system including a cooling chamber and a heat exchange device, means responsive to'the temperature of said chamber for controlling the operation of said system, differential means serially connected with said responsive means for maintaining a predetermined temperaturedifference between said cooling chamber and said heat exchange device, and means in said chamber for retarding. the action of said responsive means.

13. In combination, a cooling chamber, a heat exchange device for extracting heat therefrom, differential means responsive to the temperature in said chamber and in said heat exchange device for-maintaining a predetermined temperature relation therebetween, and means responsive to the temperature in said chamber for. maintaining a predetermined temperature in said chamber, said differential means and said last named means being connected in series relation.

14. In combination, a cooling chamber, a heat exchange device for extracting heat therefrom, differential control means responsive to the temperatures of said chamber and said heat exchange device for maintaining a predetermined temperature relation therebetween, and thermallysensitive means responsive to the absolute temperature in said chamber for controlling the temperature in said chamber.

15. In combination, a cooling chamber, a heat temperature difference between said chambers, and means responsive only to the temperature in one of said chambers for controlling the absolute temperature in said chamber.

JOHN A. DIENNER. JOHN E. GARDNER. 

